Is Macrobid (nitrofurantoin macrocrystals) an oral tablet or a capsule?

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Last updated: March 20, 2026 • View editorial policy

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Macrobid Formulation

Macrobid is a capsule, not a tablet. 1

Formulation Details

  • Macrobid is specifically formulated as a hard gelatin capsule containing 100 mg of nitrofurantoin in a dual-release system. 1

  • The capsule contains two distinct forms of nitrofurantoin:

    • 25% macrocrystalline nitrofurantoin (slower dissolution and absorption) 1
    • 75% nitrofurantoin monohydrate in a powder blend that forms a gel matrix upon exposure to gastric and intestinal fluids, providing extended release 1

Clinical Relevance of the Capsule Formulation

  • The capsule formulation should be taken with food to increase bioavailability by approximately 40%, which is critical for achieving therapeutic urinary concentrations. 1

  • This dual-release capsule design provides sustained urinary excretion of nitrofurantoin over 24 hours, with approximately 20-25% of the dose recovered unchanged in urine. 1

Common Pitfall

  • Do not confuse Macrobid with Macrodantin—while both are capsules containing nitrofurantoin, Macrodantin contains only macrocrystalline nitrofurantoin, whereas Macrobid uses the dual-release formulation described above. 1

References

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